fiddlecollector

You may not be wrong, i`m thoroughly confused by the OP`s wood . Ive never seen such a huge difference between the inside and outside before , maybe if the spindle had been sitting around for 300 years (which i doubt). Id be curious if the OP cold put some ammonia or acid on it and see what colour change they get. Even with chemicals its a huge difference. The only thing apart from dye i can think of would be something like conc. sulphuric acid which would char the outside.

For comparison here some photos of a bow blank of Gombeira ,showing sapwood (yellow) and dark heartwood. The sapwood is as hard and heavy as the heartwood. the endgrain has similar random smallish pores similar to your example.

I m even more confused, maybe the spindle blank was treated with some chemical to get that colour on the outside. I also dont think its camelthorn the endgrain is wrong. I see german suppliers selling camelthorn bow blanks over the last 5 years or so and they dont look like camelthorn either. Camelthorn is a very reddish brown coloured heartwood and the camelthorn bow blanks are a rather plain yellow . The sapwood on camelthorn is pale and full of cracks and checking. So dont know what places like Espen are selling as camelthorn. I suspect a related species of acacia.

Im confused what im looking at. Are you refering to the yellow wood or the dark brown wood?? If its both thats a hell of a colour difference to darken from yellow to dark brown??? The yellow coloured wood looks like sap wood of many ironwood species. It could also be easily yellow pernambuco.

Fish glues particulary sturgeon is thinner , the protein molecules are smaller and so can penetrate more . If it causes problems maybe you could size the whole plates with the same.

The drill press looks like a walker turner and the thing on the left hanging down possibly an old foredom rotary tool.

If it were casein plastic then bugs will munch on that as well.

The stick has a peccate-ish head. i suspect the stamp was added later, most amourette bows werent stamped ,same with ironwood bows. Some idiots start windings by drilling a tiny hole and poking the start of the wire in to secure it ,may be the end of the wire that has snapped off in the hole.. The crack/split may or may not be a problem depending on which way the grain runs through the stick.. Bows have survived for decades with cracks like that near the handle end.

Ive just been using bioethanol in the UK ,cheap and doesnt smell .Is it not available in California from bioethanol fire stores or amazon. It works great in spirit burners and in french polish.

Amourette is whats also known as snakewood, but with less figure than what you generally see. Baroque bow makers did use the figured type alot though and still do.

Andres do you mind sharing what your` worrisome discrepancies are `, just interested as an art lover !

https://www.theguardian.com/artanddesign/2020/jun/22/experts-call-for-regulation-after-latest-botched-art-restoration-in-spain

Sorry mistakenly thought the ships as well were treated ,but apparently they were mainly treated with linseed oil and creosote as you`ve mentioned. This is an interesting paper on treating wooden artifacts, mostly detroyed by alum treatment.. https://www.diva-portal.org/smash/get/diva2:1234551/FULLTEXT01.pdf

I would say one of the major contributors to the cracking has been the alum treatment the ships have had since the late 19th century. Its been shown to almost completely degrade the cellulose and hemicellulose content of the wood ,its is those that hold the wood together. On the Mary Rose which is about half the age i think they used something like strontium carbonate to get rid of the high acidity .